On 17/03/2021 11:49, Paolo Bonzini wrote:
On 17/03/21 08:45, Emanuele Giuseppe Esposito wrote:
+ struct kvm_msr_list features_list;
buffer.header.nmsrs = 1;
buffer.entry.index = msr_index;
+ features_list.nmsrs = 1;
+
kvm_fd = open(KVM_DEV_PATH, O_RDONLY);
if (kvm_fd < 0)
exit(KSFT_SKIP);
+ r = ioctl(kvm_fd, KVM_GET_MSR_FEATURE_INDEX_LIST, &features_list);
+ TEST_ASSERT(r < 0 && r != -E2BIG, "KVM_GET_MSR_FEATURE_INDEX_LIST
IOCTL failed,\n"
+ " rc: %i errno: %i", r, errno);
Careful: because this has nsmrs == 1, you are overwriting an u32 of the
stack after struct kvm_msr_list. You need to use your own struct
similar to what is done with "buffer.header" and "buffer.entry".
r = ioctl(kvm_fd, KVM_GET_MSRS, &buffer.header);
TEST_ASSERT(r == 1, "KVM_GET_MSRS IOCTL failed,\n"
" rc: %i errno: %i", r, errno);
More in general, this is not a test, but rather a library function used
to read a single MSR.
If you would like to add a test for KVM_GET_MSR_FEATURE_INDEX_LIST that
would be very welcome. That would be a new executable. Looking at the
logic for the ioctl, the main purpose of the test should be:
- check that if features_list.nmsrs is too small it will set the nmsrs
field and return -E2BIG.
- check that all MSRs returned by KVM_GET_MSR_FEATURE_INDEX_LIST can be
accessed with KVM_GET_MSRS
So something like this:
set nmsrs to 0 and try the ioctl
check that it returns -E2BIG and has changed nmsrs
if nmsrs != 1 {
set nmsrs to 1 and try the ioctl again
check that it returns -E2BIG
}
malloc a buffer with room for struct kvm_msr_list and nmsrs indices
set nmsrs in the malloc-ed buffer and try the ioctl again
for each index
invoke kvm_get_feature_msr to read it
(The test should also be skipped if KVM does not expose the
KVM_CAP_GET_MSR_FEATURES capability).
Thank you for the feedback, the title is indeed a little bit misleading.
My idea in this patch was to just add an additional check to all usages
of KVM_GET_MSRS, since KVM_GET_MSR_FEATURE_INDEX_LIST is used only to
probe host capabilities and processor features.
But you are right, a separate test would be better.
Thank you,
Emanuele
